RatedrillGet fluent in the math of money.
Interest, annuities, loans, NPV and business math, drilled with fresh numbers on every attempt. Solve it your way, then see the formula, the calculator keystrokes and the Excel version.
Read it, solve it, see why.
- 01Read a real scenarioA savings goal, a mortgage, a project or a supplier's terms, with numbers you would see at work.
- 02Enter one numberUse a financial calculator, Excel or a pencil. Draw the cash flow timeline if it helps.
- 03Learn from the checkSign error, factor of 12, wrong timing or early rounding. Hints and the worked answer follow.
Fresh numbers, every attempt. Each of the 53 problem types is a template, not a fixed question. Press New numbers and the loan, the rate and the term change, so you learn the method, not the answer.
Five levels, from compound interest to WACC.
| 01 | Basics | Simple vs compound interest, future and present value of a lump sum, time to double, the rate or years to reach a goal, effective rates and continuous compounding. |
| 02 | Annuities | Savings plans, payment streams, annuity due vs ordinary, payment to reach a goal, perpetuities, growing perpetuities and growing annuities. |
| 03 | Loans | Mortgage and car payments, balance after k payments, total interest, interest and principal in payment k, extra payments, balloons and the APR behind a payment. |
| 04 | Investments | NPV, IRR, payback and discounted payback, profitability index, bond price, yield to maturity, current yield, holding period return and CAGR. |
| 05 | Business math | Break-even units and revenue, markup vs margin, the cost of skipping a 2/10 net 30 discount, SL, DDB and SYD depreciation, real returns, WACC and after-tax cost of debt. |
Timed mode for real speed.Each problem gets a clock. Hints and answers stay locked until time is up, and your best times are kept.
Start free. Pay once you are hooked.
Pro
- Annuities, loans, investments and business math
- Worked solutions with keystrokes and Excel formulas
- Progress and best times saved to your account
Payments open soon. The free exercises work now.
Questions
Who is this for?
Anyone who works with money math: business and finance students, analysts, bankers, loan officers, bookkeepers and small business owners who want to do these calculations quickly and correctly on a financial calculator or in Excel.
What does fresh numbers every time mean?
Each problem type is a template. Every attempt picks new, realistic inputs, such as a new loan amount, rate or term, so you practice the method instead of memorizing an answer. New numbers gives you another version of the same problem at any time.
How are answers checked?
Money answers count when they are within one cent or 0.01%, whichever is larger. Rates count within 0.01 percentage points. When an answer is off, the checker tells you the likely mistake: a sign error, a factor of 12 or 100, annual instead of monthly compounding, payments at the start instead of the end of the period, or rounding too early.
Do I need a financial calculator?
No. Any calculator with powers and logarithms works, and every worked solution shows the formula, the TVM keystrokes (N, I/Y, PV, PMT, FV with the sign convention) and the matching Excel formula.
Do I need an account?
No. The first five problem types work without one and save progress in your browser. A free account saves progress across devices, and Pro unlocks the rest.
How do I cancel the monthly plan?
Open Account and choose Cancel subscription. That is the whole process: you keep Pro until the end of the period you paid for and are not charged again. If Pro is not for you, you get a full refund within 14 days of paying.
What if my answer is right but marked wrong?
Answers are checked on the result they produce, not on how they are written, so any correct answer passes. If a check still gets it wrong, use the report link under the result. Reports are reviewed, and a check that is wrong gets fixed.